Preparation method of water-soluble sand core used for aluminium alloy or magnesium alloy thin wall complex casting

Abstract

The invention discloses a preparation method of a water-soluble sand core used for an aluminium alloy or a magnesium alloy thin wall complex casting, and the method is as follows: (a) at room temperature, preparing magnesium sulfate heptahydrate and plasma water into a 20% to 30% magnesium sulfate aqueous solution, adding specific amount of octadecahydrate aluminum sulfate and an additive into the 20% to 30% magnesium sulfate aqueous solution, and heating to 60 to 80 DEG C to prepare a compound binder; (b) premixing homogeneously foundry raw sand, adding a composite binder to obtain mixture core sand; (c) putting the obtained mixture core sand into a core making mould, then putting the mixture core sand together with the mould into microwave environment for heating, removing and demoulding to obtain a water-soluble sand core product. By the method, the water-soluble sand core with good room temperature strength, moisture resistance, chemical stability and low gas-forming amount can be produced, and the water-soluble sand core especially has excellent water soluble collapsibility after casting, and causes no damage to the casting and no pollution to the environment.

Description

technical field [0001] The invention belongs to the technical field of aerospace materials, and more specifically relates to a method for preparing a water-soluble sand core of an aluminum alloy or magnesium alloy thin-walled complex casting. Background technique [0002] In the aerospace manufacturing industry, in order to reduce the mass and improve the structural strength and maneuverability of aircraft and spacecraft, integral thin-walled structural parts are increasingly used, such as thin-walled frames, wall panels, wing ribs and Engine turbine blades, etc. Correspondingly, the requirements for thin-walled structural parts of these metal alloys (such as aluminum alloys and magnesium alloys) are also very stringent, especially when such thin-walled structural parts have complex inner cavity structures or thin, curved and long holes When the sand core is a composite sand core, it will make it very difficult to clean the casting after casting, so a higher collapse perfor...

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Problems solved by technology

For example, He Jiaqing etc. have proposed a kind of magnesium sulfate water soluble core, but it adopts single magnesium sulfate solution as binding agent, and adding amount is bigger and intensity is not high, and the adding of kaolin makes sand core gas generation increase easily; Disclosed in CN101391453A A sand core made of sodium silicate sand was developed, but it has a large hygroscopicity and a large loss of sand core strength in an air environment, requiring pouring in a very short time, which is difficult to operate, and in some low heating temperature ranges, the water-soluble effect Poor; In addition, US7000680B discloses the method for preparing magnesium sulfate water-soluble core in the mode of blowing hot air, but its binder addition amount is still relatively large, correspondingly causes the sand core gas generation to increase

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